Ephedrine (l-form) is an alkaloid, which was initially purified from Ephedra plant. The extract form Ephedra has been used in China for medicinal purposes for several thousand years. Ephedrine acts as an agonist at alpha- and beta-adrenergic receptors and indirectly causes the release of norepinephrine from sympathetic neurons. The drug crosses the blood brain barrier and stimulates the central nervous system. Ephedrine products are now banned in many countries, as they are a major source for the production of the addictive compound methamphetamine. FDA has approved ephedrine only for the treatment of clinically important hypotension occurring in the setting of anesthesia.

L-Norpseudoephedrine is a psychostimulant drug of amphetamine family, first isolated from an Ephedra species. It is one of the two enantiomers of norpseudoephedrine, less potent that D-Norpseudoephedrine. L-Norpseudoephedrine is a norepinephrine and dopamine releasing agent, and has thermogenic and anorectic effect.

Pseudoephedrine is a sympathomimetic drug. Pseudoephedrine acts as an adrenomimetic and inhibitor of monoamine transporters. Ephedra sinica, a species of ephedra (ma huang), contains ephedrine and pseudoephedrine. Ephedra has been found to stimulate the nervous system, increase airflow into the lungs and constrict blood vessels. In combination with caffeine, ephedra appears to cause weight loss. Pseudoephedrine is a decongestant that shrinks blood vessels in the nasal passages. Pseudoephedrine is used to relieve nasal or sinus congestion caused by the common cold, sinusitis, and hay fever and other respiratory allergies.

Phenylpropanolamine belongs to the sympathomimetic amine class of drugs and is structurally related to ephedrine. The effects of phenylpropanolamine are largely the result of alpha-adrenergic agonist activity resulting from both direct stimulation of adrenergic receptors and release of neuronal norepinephrine. Phenylpropanolamine is mainly used as a nasal decongestant. Phenylpropanolamine is also used as anorexiant in obesity and to treat urinary incontinence in veteranary. Phenylpropanolamine containing products has been withdrawn by FDA due to the association of phenylpropanolamine use with increased risk of hemorrhagic stroke.